When ore is mined, it is generally in large fragments that must be reduced in size for further refining. Several types of ore comminuters or reducers can be used, one of which takes the form of a large cylindrical closed drum that is rotated on a horizontal axis in a single direction or in both directions (i.e., bi-rotationally). Ore is introduced into one end of the drum through an inlet, and, after reduction or comminution, the reduced ore is discharged through an outlet in the opposite end. Within the drum, the charge of ore fragments rests at the bottom of the rotating drum. As the drum rotates, part of the ore charge is carried upwardly along the irregular inner surface of the drum until the carried fragments drop from the drum surface due to gravity, tumbling back onto the ore charge and breaking the fragments. This continuous process results in reduction of the fragments to a predetermined size, at which time they are discharged from the mill.
The inner cylindrical surface of the drum is fitted with a liner assembly made up of individual liner segments arranged in circumferential and axial rows. The liner segments can be made using various techniques and materials. For example, the liner segments can be cast from alloys, or can be made from rubber, ceramics, or magnetic materials.
Typically, the liner segments are designed to optimize the wear rate while avoiding breakage by being too hard and brittle. Each of the liner segments has a slightly convex bottom surface that conforms to the radius of curvature of the cylindrical drum and a top surface that is irregular in shape. The liner segments together typically define axially extending ridges and valleys that facilitate lifting of the ore fragments as the drum is rotated. Examples of such liner assemblies are disclosed in U.S. Pat. Nos. 4,018,393, 4,165,041, 4,235,386, 4,243,182, 4,319,719, 6,082,646, and 6,343,756, all of which are hereby incorporated by reference in their entireties.
Ore comminuting mills of this type generally run twenty-four hours a day for economic efficiency. The continuous process wears the liner segments down over a period of time, which will depend on the type of ore and application, after which the liner assembly must be replaced. Because down time of the ore comminuting mill adversely effects the economic efficiency of the process, it is desirable to identify when the liner assembly has been worn to the point of requiring replacement, and to change the liner assembly as quickly as possible. In addition, various other operating factors can affect the wear rate of the liner assembly and overall performance of the mill.
Current methods for measuring the wear of liner assemblies typically involve the manual measurement of multiple segments of the liner to estimate wear. For example, some processes require twenty or more measurements to be taken to estimate liner wear. This measurement process can be tedious and time-consuming. Further, the mill must be shut down during the process. It is therefore desirable to optimize the ease and speed at which performance determinations such as wear can be made.